1. Field of the Invention
The present invention relates to a heat exchanger, which is installed in a vehicular air conditioning apparatus that performs temperature adjustment of a vehicle compartment, whereby the heat exchanger is used by the vehicular air conditioning apparatus for cooling and heating air that is blown into the vehicle compartment.
2. Description of the Related Art
A vehicular air conditioning apparatus, which is mounted in a vehicle, for example, is equipped with a first blower for drawing in air from the vehicle interior into a casing, and a second blower for drawing in air from the interior and exterior of the vehicle into the casing. In this case, for example, air that is introduced from an internal air introduction port by rotation of the first blower is heated by a first heat exchanger, passes through a first air passage, and is blown out from face blow-out ports, or foot blow-out ports in the vehicle compartment from a blow-out port. Together therewith, air that is introduced from an external air introduction port by rotation of the second blower, after being heated by a second heat exchanger, passes through a second air passage and is blown out from defroster blow-out ports.
Further, the above-mentioned heat exchanger, for example, comprises a plurality of tubes which are arranged in two layers in a thickness direction of the heat exchanger, and fins which are bent or folded in an undulating or wavy shape, and which are disposed between the tubes. Plural louvers, through which air passes, are provided in the fins.
With a vehicular air conditioning apparatus equipped with this type of heat exchanger, there is a tendency for the air supplied from the first blower and the air supplied from the second blower to become mixed inside of the heat exchanger. Thus, as disclosed in Japanese Laid-Open Patent Publication No. 10-278547, in order to prevent mixing of air inside the heat exchanger, a heat exchanger is used in which a louverless portion, which does not contain any louvers therein, is set and provided within a portion of the fins, the louverless portion being arranged at a boundary region between a passage through which the air from the first blower flows and another passage through which the air from the second blower flows.
On the other hand, when the fins constituting the aforementioned heat exchanger are fabricated, as disclosed in Japanese Laid-Open Patent Publication No. 2002-205122, a band plate is supplied between a first press-forming roll and a second press-forming roll, which are mutually enmeshed together, such that simultaneously with bending of the band plate in an undulating shape and forming the fins by rotation of the first and second forming rolls, plural louvers are formed in the fins by means of louver cutting teeth, which are provided in the first and second forming rolls.
However, in the case that fins having a louverless portion therein, as discussed above, are formed by the first and second forming rolls, since the louver cutting teeth need not be provided at a region corresponding to the louverless portion, when the fins are fabricated, the need arises for the region where the louverless portion resides and a region in the direction of rotation of the first and second forming rolls to be positioned mutually with respect to each other. As a result, the preparations for the forming step become more complex, and productivity tends to be lowered.
Further, normally, in the case of forming the fins, the first and second rolls are rotated multiple times (through multiple rotations), in which fins having a predetermined length in the longitudinal direction are to be formed. However, in the case that the first and second forming rolls are rotated multiple times while a louverless portion is provided, the louverless portion ends up being formed at two or more locations in the fin. Furthermore, in the case that only a single louverless portion is sought to be formed, it is necessary to fabricate the entire fin by effecting only one rotation of the first and second forming rolls. In this case, the first and second forming rolls must be made larger in diameter, accompanied by an undesirable increase in scale of the forming apparatus.